1. Field of the Invention
The present invention relates to a capping mechanism for protecting recording means for effecting recording by discharging ink toward a recording medium, and an ink jet recording apparatus using such a capping mechanism.
2. Related Background Art
As recording apparatuses having a printer, copier or facsimile function, or recording (printing) apparatuses used as a an output device for a composite electronic equipment including a computer or a word processor or for a work station, an ink jet recording apparatus in which recording is effected by discharging ink toward a recording medium (recording material) such as paper, cloth, plastic sheet or OHP sheet in response to image information (recording information) has been popularized. Further, there are various requirements for materials of the recording media, and, in recent years, development for meeting such requirements has been progressed, so that recording apparatuses in which cloth, leather, non-woven fabric or metallic sheet, as well as paper (including thin paper or processed paper) or resin thin plate (OHP sheet or the like) as normal recording medium, is used as a recording medium has been proposed.
The ink jet recording apparatus has widely been used as a printer, a copier and a facsimile because it has low noise and low running cost and it can easily be made compact and it permits color recording. Plural discharge ports for discharging ink droplets are provided on a front face of recording means (ink jet recording head) of the ink jet recording apparatus, and each discharge port has of dimension of about several tens of xcexc. However, recently, the dimension of the discharge port has been reduced more and more as high quality recording has been progressed. The ink droplet is discharged from the discharge port in response to a discharge signal processed in the recording apparatus on the basis of recording data sent from a host machine, thereby recording an image (including a character and/or symbol) on the recording material.
In the above-mentioned ink jet recording apparatus in which the recording is effected by discharging the ink from the recording means toward the recording medium, since the recording is effected by discharging the ink from the minute discharge port, the discharge port may be clogged to cause poor discharging (including non-discharging), thereby deteriorating quality of the recorded image. To avoid this, a recovery unit for maintaining and recovering ink discharging performance of the recording means has been used. As an example, the recovery unit may include a capping mechanism for capping the discharge port of the recording head, suction means adapted to be connected to the capping mechanism in a capping condition and designed to maintain and recover the ink discharging performance by refreshing the ink in the discharge port by sucking and discharging foreign matters such as viscosity-increased ink and/or bubble(s) from the discharge port by negative pressure generated in the capping means by operating a pump, and wiping means for wiping and cleaning foreign matters such as ink adhered to a discharge port face of the recording means.
That is to say, in the ink jet recording apparatus, in order to protect the discharge port face of the recording head (recording means) or to eliminate the clogging due to dirt and/or fixed ink adhered to the discharge port face, the capping mechanism including a rubber cap is provided so that the discharge port face can be capped if necessary. Since the cap must be retarded to a retard position to avoid interfere between the recording head and the cap during the recording operation, the cap is designed to be movable. For example, the cap may be slid laterally (in a carriage scanning direction) to effect capping and retarding or may be shifted in a vertical direction to effect capping and retarding.
However, in the former slide-type cap arrangement, since a carriage must be shifted in a capping areas exceeding out of a recording area, a width-wise dimension of the recording apparatus is increased. In order to avoid such bulkiness of the recording apparatus, it is preferable that the capping and uncapping (retarding) are effected by shifting the cap in an abutting/spacing direction with respect to the discharge port face (for example, a vertical direction). Such a conventional technique is disclosed in Japanese Patent Application Laid-Open No. 2000-103072, in which a cap arm for holding a cap is rotatably supported and a cap position is controlled by a cap cam and a cap arm spring. In this arrangement, a capping (closing) force of the cap relies upon the cap arm spring and a closing ability around the abutment area between the cap and the discharge port face relies upon elasticity of the cap itself. However, due to dispersion in tolerance of parts, if great inclination (displacement) occurs between the recording head and the cap, such displacement cannot be absorbed only by the elasticity of the cap, with the result that partial leakage of the abutment area between the cap and the recording head may occur, thereby making the normal capping operation impossible.
In order to eliminate such inconvenience, it is considered that equalization properties of the contact area of the cap (uniform contacting ability around the cap) is enhanced by interposing a cap spring (urging spring) between the cap and the cap arm to follow the inclination of the recording head thereby to maintain the closing or sealing condition. However, with this arrangement, in the capping condition, the cap arm spring and the cap spring (urging spring) affect an influence upon each other, with the result that a positional posture of the cap may become unstable.
As a technique similar to the above-mentioned conventional arrangement, there is a technique in which the cap is biased by a spring to be retarded from the recording head. That is to say, in this technique, the cap is forcibly shifted in the closing direction by a cam in opposition to the spring acting toward the retard direction and the closing position (capping position) is determined by dimensions of various parts. In this arrangement, since the closing ability of the abutment area between the cap and the recording head becomes unstable, in order to correct such unstability, a cap spring is disposed between the cap and a cap holding member so that equalization properties of the cap (uniform contacting ability around the cap) is enhanced by the spring. In such an arrangement, unlike to the conventional technique in which the cap is forcibly held at the closing position by the cam, since the cap holding member is stably supported at the closing position (capping position) by the cam, capping pressure is determined by the cap spring, with the result that the positive capping condition can be maintained while ensuring the equalization function (uniform contacting ability around the cap).
However, in such an arrangement, if the apparatus is left as it is for a certain term in the capping condition, the cap may be fixedly adhered to the discharge port face of the recording head with which the cap is closely contacted, with the result that the cap cannot be separated (peeled) from the discharge port face only by the force of the returning spring, thereby generating error in the opening/closing operation of the cap. Incidentally, also in this case, although the operational error can be eliminated by setting the spring force of the returning spring to have a great value, in this case, load torque is also increased accordingly, with the result that additional countermeasure to torque increase of a drive motor and deformation/wear of various parts is required, thereby increasing the cost of the apparatus. Namely, it is not preferable to have excessive burden due to rare inconvenience generated by the adhesion between the recording head and the cap.
An object of the present invention is to provide a capping mechanism in which, even if a cap is adhered to recording means, an opening/closing operation of the cap can be effected positively and correctly without increasing a returning force, and an ink jet recording apparatus using such a capping mechanism.
Another object of the present invention is to provide a capping mechanism for protecting recording means for effecting recording by discharging ink toward a recording medium, which comprises a cap movable in directions along which the cap can be contacted with and separated from a discharge port face of the recording means, cam means for controlling a position of the cap, shifting means for shifting the cap in the above-mentioned directions, and biasing means for biasing the cap to be separated from the discharge port face, and in which the cam means includes first and second cams and the shifting means includes first and second engagement portions so that the first cam is normally engaged with the first engagement portion, and, when the first cam is disengaged from the first engagement portion, the second cam is engaged with the second engagement portion.
A further object of the present invention is to provide a capping mechanism for protecting recording means for effecting recording by discharging ink toward a recording medium, which comprises a cap movable in directions along which the cap can be contacted with and separated from a discharge port face of the recording means, cam means for controlling a position of the cap, and biasing means for biasing the cap to be separated from the discharge port face, and in which the cam means includes first and second cams and a cap holding member for holding the cap includes first and second engagement portions so that the first cam is normally engaged with the first engagement portion, and, when the first cam is disengaged from the first engagement portion, the second cam is engaged with the second engagement portion.
According to the present invention, even if the recording means is adhered to the cap, an adhered condition can be released without aiding of a force of the biasing means, with the result that an error in an opening/closing operation of the cap due to the adhesion between the recording means and the cap can be eliminated, thereby realizing correct opening/closing operation of the cap, and, since setting force of the biasing means is not required to be increased, increase in load torque and increase in deformation/wear of parts can be eliminated.